Magnetostrictive signal translating device



Dec.30, 1947.Vv 4 .RQ M'. BozoRTH w 2,433,337

Y GRETQSTRICTIVE SIGNAL TRNSLATNG DVICE Filed aan. l, 194:5

. may be oi nickel or Patented Dee. so, 1947 MAGNErosrmc'rlvE SIGNAL TRANSLAT- f me. pnvron VRichard M. nozorth'. short mus, N. J., assigner' to Bell Telephone Laboratories, Incorporated, New York, N. Y., a .corporation of New York Application January 19, 194s, serial No. 472,843

1'o claims. (ci. r11-sse) This invention relates to magnetostrictive lSignal translating devices and moreI particularly to such devices especially suitable for use as transmitters and receivers signaling equipment.

One object of this invention is to increase the sensitivity of magnetostrictive signal translating devices.

Another object of this invention is to simplify the construction of magnetostrictive hydrophones of substantial power capacity.

A further object of closed magnetic loop. Y

In one illustrative embodiment of this invention, a hydrophone comprises a magnetostrictive core in the form of a closed magnetic loop having two parallel legs, a magnet for polarizing these legs and a slgnalcoil electromagneti'cally coupled to the core, the core being mounted to allow expansionI and contraction of the parallel legs whereby the core vibrates in response to signal currents inthe coll or conversely currents are induced in the coil in accordance with elongations and contractionsof the core.

In accordance with one feature of this invention, the parallel legs of the core are constructed of different magn tostrictive materials. 'one leg being of a materia having a negative magnetostrictive coefilcient and the ,two legs are polarized longitudinally and in the same direction. For example, one leg a Permalloy containing more than 81 per cent'nickel and the other leg may be of a Permalloy containing from about 30 to 80 per cent ci nickel and the balance principally iron, and characterized by a high initial permeability.

When' the core is subjected vto stresses' longi- .tudinally of the legs, as in sional waves, the flux in these legs' varies in accordance with'the stresses produced therein. Because oi.' the. dierent magnetostrictive characteristics of the materials oiiwhich the two legs `are composed, the flux variations in the two legs are likewise dinerent. `That, is, when the creases. and vice versa. inasmuch' as the two legs are ypolarized in the same direction, the flux changes in the two legs are cumulative considered around the closed magnetic loop, sothat -a low reluctance series path for 'the-varying' -nux is realized with attendant high sensitivity.

in supersonic submarine Conversely when the ilux in the loop is varied in accordance with a signal current supplied to this inventio'h is to obtain '1 substantially rectilinear elongation and contraction of a magnetostrictive core constituting aand the other of a material having a positive magnetostrictive coeiilcient.'

` flxedly secured. The core, which is of laminated construction, is rectangular in form and comprises parallel, longitudinal legs Il and |2-ar1d transverse arms I3. Each lamination of the core, l

response to compresux in one leg increases, that in the other de Aof the device shown in Fig. 1.

the signal coil, the Apath for the varying flux being serially around the loo-p, the twolegs elongate and contract cophasically in the same direction.

In accordance with another feature oi vthis invention, the core is formed of rectangular lamiriae, each lamination fbeing composed of two L shaped portions, theend of the shorter arm of each portion being joined to the end of the longer arm of the other portion, and the laminae are `mounted in alternate,. interleaved face to face relation, that is, in suchmanner that the shorter or transverse arms of the core are composed of equal numbers of parts of the different magneto'- strictive materials. y

vThe invention and the aorenoted and other features thereof will be understoodmore clearly and fully from the following detailed description with reference to the accompanying drawing in which:

Fig. 1 is a front elevational view ofv a magnetostrictive translating device illustrative of one embodiment of this invention, the coil windings being shown in section; I

Fig. 2 is a side elevational view of the device shown in Fig. 1;

Fig. 3 is a diagrammatic, perspective exploded view illustrating the construction and alternate interleaved relation of the laminas constituting the core ofthe device shown in Fig. 1;

Fig. 4 is a diagrammatic view. illustrating the paths oi the polarizing and varying fluxes inthe core in the' device shown in Fig. 1; and

Fig.' 5 isr anelevational view of Referring now to the drawing, the translating device illustrated in Figs. 1 to 4 comprises a rigid, fixed mount or support Ill to which the core is as shown clearly in Fig. 3, is composed of two L-shaped sections, ,the shorter arm of each section abutting and being joined to the longer arm of theother section, and the'several laminae being clamped together as by bolts H extending therethrough. y y

The two l.shaped sections ef each lamination areformed of materials having dinerent masnetostrictive coefficients. For example, the section having the long arm Ila and shorter arm lla may be of nickel, which contracts when the a modiilcation y flux therethrough increases, the contraction being in the direction of the dug change; the sec- :tion having the long arm. |24 and shorter arm I3b may be of 45 per cent Permalloy, which expands, in the direction of the iiux change, when the. ux therethrough increases. Thei magnetostrictive coeiiicientsV of the two materials are opposite in sign and substantially equal in magnitude. As illustrated in Fig. 3, the laminae are arranged in such manner that the arms I3 of the core are composed of equal numbers of alternately related arms 13a and lab of the two magnetostrictive materials so that, in these arms I8, the magnetostrictive eiects of the constituent parts I3a and Ilb substantially neutralize each other. The core, then, comprises, in eiect. longitudinal arms il and i2 of opposite mag- -netostrictive character connected by transverse passed by winding's 2D, which are connected in.

series aiding and are free from the legs so as not to impede elongation and contraction of the latter.

l .As-is apparent from the drawing, one end oi the core is secured to the mount or support lil, by the 'mounting screws l@ and bracket 2l, and thus is fixed against movement. The other end of the core may be connected in suitable .ways to a diaphragm, not shown, for subjecting the legs il and I2 to longitudinal stresses.

The operation of the device willbe understood from the following analysis with particular reference to Fig. 4. If the magnet It is poled as shown in this figure, the polarizing direct current iiux will traverse the legs li and I2 in the same direction as indicated by the full arrows qs. If the core is subjected to a varying pressure, indicated bythe arrows P, corresponding for example to a compressional wave, the4 legs II and l2 will elongate and contract. in unison. Hence, the ux in the legs II and I2 will vary in accord ance with the pressure, the flux changes. at any elongation and contraction and this motion may be conveyed in suitable manner to a diaphragm waves corresponding to the signal current supor other radiating member to propagate signal plied to the windings 20. l

In the modification illustrated in Fig. 5, the laminae of the core are composed of C-shaped andi-shaped portions joined to form a rectangular' loop, the two portions being of different magnetostrictive materials as in the device illustrated in Figs. 1 to 4. Also, as in the' latter device, the' laminae of the core in the device shown in Fig. 5 are interleaved in alternate relation so that each of the arms I3 is composed of alternate sections of the dierent materials.

Although specic embodiments of the invention have been shown and described, it will 'be understood that they are but illustrative and that various modiiications may be made therein. For

example, although the core has been shown s pendedclaims.

instant, in the two legs being opposite in direction, as indicated for one instant by the dotted arrows Aqs, due to the difference in the magnetostrictive coefficients of the materials of these two legs. Hence, the varying flux component flows serially around the loop defined by the core and corresponding currents, in series aiding, are developed in the windings 2li. It will be noted that the varying ux traverses a closed magnetic circuit of low reluctance. The arms I3, because of their construction, are substantially neutral magnetostrictively as pointed out heretofore.

If the device is operated in the reverse manner, that is if a signal current is supplied to the windings 20, the' iiux changes produced in the two legs II and I2 are opposite in direction at any instant, and the two legs will change in length cophasically and in the same direction. For example, if the ilux in the leg II is increased, this leg will contract; at the same time the ux in the leg I2 is decreased and this leg likewise contracts. The arms I3 being magnetostrictively.

inert, the legs .II and i2 will execute rectilinear What is claimed is: l

1. A magn'eatostrictive signal translating device comprising a' core having lspaced parallel legs, one of said legs being of a material having a negative magnetostrictive coeiiicient and the other leg being of -a material having a positive magnetostrictive coeicient, means for polarizing said legs longitudinally and in the same direction, and means for driving said legs longitudinally and inthe same direction.

2. A magnetostrictivesignal translating device comprising a hollow rectangular core two parallel legs of which are of materials having'rnagnetostrictive coefficients diierent in sign, means for polarizing said two legs longitudinally and I in the same direction, and signal coil means electromagnetically coupled to the ux' path around said core including said legs magnetically in series. A

3. A magnetostrictive signal translating device comprising a core having two parallel legs, one of said legs being of nickel and the other of said legs being of an alloy composed of the order of 45 per cent nickel and balance chiey iron, means for polarizing said legs longitudinally and in the same direction, means for driving said legs longitudinally and in the same direction.

4. A magnetostrictive signal translating device comprising a hollow rectangular core one leg 'of which is composed of a material having a negative magnetostrictive cociiicient, the opposite leg of which is of a material having a positive magnetostrictive coefiicient and the other two legs 'of which are laminated, alternate laminae being oi. said rst material and the remaining4 laminae being of said second material, means for polar-4 izing said first and opposite legs longitudinally and in the same direction, and a signal coil electromagnetically coupled to said core.

5. A magnetrostrictive signal translating vde- Also it may 5 eicient of the other of which is positive, said laminations being arranged in interleaved relation such thatone of said longitudinal legs is composed of laminae sections of one of said materials, the other oi.' said legs is composed of laminae sections of the other of said materials and each of said arms is composed of laminae sections of both of said materials, means for polarizing said legs longitudinally and in the same direction, and a, signal coil electromagnetically coupledto said core. y a

6. A magnetrostrictive signal translatingdevice comprising a hollow rectangular core composed of a plurality of laminae, each of said laminae comprising two L-shaped sections of different materials one of which has a positive and the other of which has a negative magnetostrictive coeillcient, said laminae being oriented such that one leg of said core. is composed of laminae sections or on`e of said materials, ,the opposite leg is composed of laminae sections of the other of said materials and theother two legs are composed of laminae sections of both of said materials in interleaved relation, means for polarizing said one and opposite legs longitudinally and in thesame direction, and a signal coil electromagnetically coupled to said core.

7. A magnetrostrictive signal `translating device comprising a core having parallel legs, one

of said legs being of a material havinga negative magnetrostrictive coefficient and the other of a material having a positive magnetostrictive coemcient, means for xing one end of each of said legs against motion, the other end of each of said legs being free to moven. means polarizing said legs longitudinally and in the same direction. andmeans for effecting elongation and contraction of said legssimultaneously 'and inthe same direction, l

8. `A magnetostrictlve signal translating de-l vice comprisinga rigid mount, a hollow rectangular core oneleg of which is of a material having a negative magnetostrictive coefilcient, the opposite leg of which is of a material having a positive magnetos'trictive coefcient, and the other two legs of which are composed of laminae, alternate laminae being of one of said materials j and the remainder of the other of said materials,

one of said other two legs being fixed to said mount, means for polarizing said rst and said opposite legs longitudinally in the same direction, and a signal coil electromagnetically coupled to said core.

9. A magnetostrictive signal translating device comprising a hollow rectangular core two opposite legs of which are of different magnetostrictive materials, one having a negative and the other having a positive magnetostrictive coemcient, the other two legs of said c ore being composed of laminae of both said materials in alternate relation, a permanent magnet having its pole-pieces opposite said other two legs, 'a signal coll electromagnetically coupled to said core, and support means for said core secured to one of saidother two legs and fixing this leg against movement. y

liO. A magnetostrictive signal translating device comprising a hollow rectangular core, composed of rectangular laminae,ieach of said laminae being formed of two L-shaped portions one of which is of nickel and the. other of an alloy v REFERENCES CITED The following references are of record inthe ille oi this patent:

' STATES PATENTS Number Name Date 1,768,377 Serduke June24, 1930 1,882,393 Pierce Oct. 11,'1932 2,249,835 Lakatos ----1 July 22, 1941 FOREIGN PATENTS l Number Country Date Germany Jan. 10, 1934 

